Cohesity fresher interview Experience

The interview was conducted on zoom and codesignal was used to write working codes for the given problems. Round 1:  Three programming questions were asked in this round (Increasing order of difficulty) :

1. First non repeating character in a very large string with only one traversal of the string.
2. https://www.geeksforgeeks.org/dsa/sliding-window-maximum-maximum-of-all-subarrays-of-size-k/ In this problem a O(n) solution was expected.
3. A dictionary of words is given. Any word is called valid, if it belongs to the dictionary. A string is given. You need to find all partitions of string such that each partition is a valid word. For eg. let the given dictionary be { man, ice, cream. go, icecream, mango } and string given to you is mangoicecream, then all the valid breakdowns are :
   1. man go ice cream
   2. man go icecream
   3. mango ice cream
   4. mango icecream

Round 2: The interview started with the discussion of one of my projects in which I had used multi threading. Various other questions like the difference between threads and processes, the scenarios in which each of them should be used, and python specific threading questions were asked (My project was in python). Two programming questions were asked after this

1. https://www.geeksforgeeks.org/dsa/maximum-profit-by-buying-and-selling-a-share-at-most-twice/
2. You are given a file of size 100 GB containing unsigned 64 bit integers. You have to write a program to sort these integers and copy it in a different file. However, usable RAM is only 2 GB. I told a approach based on merging k sorted arrays and using intermediate files. The interviewer was satisfied with the approach.

Round 3: This interview was with one of the directors who had around 20+ patents to his name. So I was a little bit nervous at the start. The interviewer gave a C code and I was asked to predict its output. I messed up and gave a wrong answer. Then the interviewer told me compile and run the program to check the output and I realised that I had made a blunder. The interviewer asked me a identify my mistake and correct it. I fortunately did that. After that the following programming question was given :

1. Given a string containing only B and W's (Black and white balls) you need to bring all white balls to the start of the string. eg if the string is "BWWB" the output should be "WWBB". The only allowed operation is swaping of elements. You cannot overwrite any of the characters. Also, expected time complexity was O(n) and expected space complexity was O(1). I gave a two pointer based approach. I was asked to code the solution and also generate test cases for the same.

Round 4: This interview was completely based on Operating systems. I was asked to design a data structure to store information about processes. I was expected to explain every single thing that I considered in the data structure even the datatypes that I used. Related questions like burst time, waiting time, etc. were asked. The interviewer was also interested in knowing how is the burst time calculated. (You cannot calculate burst time of a process. We study burst time in scheduling only for the purpose of benchmarking). Got the offer after a week!